CODEWORD PERMUTATION AND REDUCED FEEDBACK FOR GROUPED ANTENNAS

• US 20080080641A1
• Filed: 09/05/2007
• Published: 04/03/2008
• Est. Priority Date: 09/06/2006
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Kim, Byoung-Hoon
• Granted Patent: US 8,798,201 B2
• Time in Patent Office: Days
• US Class Current: 375/299
• CPC Class Codes: H04B 7/0632 Channel quality parameters, e.g. channel quality indicator [CQI]
• CPC Class Codes: H04B 7/0641 Differential feedback
• CPC Class Codes: H04B 7/0691 using subgroups of transmit antennas
• CPC Class Codes: H04L 5/0023 Time-frequency-space

Abstract

Systems and methodologies are described that facilitate reducing feedback required to be, transmitted on a reverse link channel in response to a forward link data transmission for multiple-input multiple-output (MIMO) wireless communication systems. In a per group rate control MIMO system, a codeword can be linked to more than one layer. Codewords are mixed among antennas in the MIMO systems based upon a symmetric permutation of antennas groups. Further, codewords are transmitted in permuted form so that receivers can reduce feedback to a base channel quality indicator (CQI) and a differential CQI. Additionally, spatial diversity is increased for each codeword improving the robustness of the system against inaccurate CQI reports.

Claims

1. A method that facilitates reducing required feedback for data rate control in wireless communication, comprising:

determining one or more groupings of a plurality of transmit antennas;

permuting. data stream codewords according to a permutation of the antenna groupings; and

transmitting the permuted codewords through the one or more of groupings of transmit antennas over a forward link channel.

2. The method of claim 1, determining one or more groupings comprises identifying active antennas among the plurality of transmit antennas and disregarding inactive antennas when formulating the one or more groupings.

3. The method of claim 2, further comprising:

determining a layer to codeword ratio; and

restricting a size of the one or more groupings to the layer to codeword ratio.

4. The method of claim 3, wherein each codeword corresponds to one layer;

5. The method of claim 3, wherein each codeword corresponds to two layers;

6. The method of claim 1, further comprising:

receiving a condensed channel quality indicator (CQI) as feedback related to transmitting the permuted codewords; and

,

adjusting at least one of a data rate, code rate, or modulation scheme of subsequent codewords transmitted based upon the condensed CQI.

7. The method of claim 6, the condensed CQI comprises a base CQI reflecting a signal quality metric of a first decoded codeword and a differential CQI reflecting a signal quality gain obtained by cancelling the first decoded codeword in decoding a second codeword.

8. The method of claim 6, the condensed CQI comprises a base CQI reflecting a signal quality metric of both a first decoded codeword and a second decoded codeword.

9. The method of claim 7, the signal quality metric is one of a signal-to-noise ratio (SNR) or signal-to-interference-plus-noise ration (SINR).

10. The method of claim 7, adjusting subsequent codewords comprises:

adjusting the at least one of a data rate, code rate, or modulation scheme of a subsequent first codeword according to the base CQI; and

adjusting the at least one of a data rate, code rate, or modulation scheme of additional subsequent codewords based upon a sum of the base CQI and a multiple of the differential CQI.

11. The method of claim 8, adjusting subsequent codewords comprises:

adjusting the at least one of a data rate, code rate or modulation scheme of subsequent first and additional codewords based upon the base CQI.

12. The method of claim 1, permuting codewords comprises distributing codewords blocks amongst all antenna groupings such that each codeword is transmitted in part over each antenna in the plurality of antennas.

13. The method of claim 1, the plurality of transmit antennas include one or more physical or virtual antennas.

14. A wireless communications apparatus employable in a multiple-input, multiple-output system, comprising:

means for identifying a level of codeword to layer correspondence;

means for formulating groups of transmit antennas based at least in part on the level of codeword correspondence; and

means for performing symmetrical permutations of at least two codewords.

15. The wireless communications apparatus of claim 14 further comprising:

means for transmitting the at least two permuted codewords through the antenna groups; and

means for utilizing feedback related to the transmission of the at least two codewords.

16. The wireless communications apparatus of claim 15, the feedback comprises a condensed CQI including a base CQI value and a differential CQI value.

17. The wireless communications apparatus of claim 15, the feedback comprises a base CQI reflecting a signal quality of the at least two codewords.

19. The wireless communications apparatus of claim 17, the memory further retains instructions related to determining a number of active antennas and identifying a level of codeword to layer correspondence.

18. A wireless communications apparatus, comprising:

a memory that retains instructions related to grouping transmit antennas, permuting codeword symbols based upon the antenna groupings and utilizing feedback to adjust transmission performance; and

a processor, coupled to the memory, configured to execute the instructions retained in the memory.

20. A machine-readable medium having stored thereon machine-executable instructions for:

grouping transmit antennas based upon a correspondence between codewords and layers;

shuffling codeword blocks across antenna groupings based upon symmetrical permutations of the groupings;

transmitting the shuffled codeword blocks via a forward link channel through the transmit antennas;

receiving a condensed feedback metric relating to the transmission of shuffled codewords; and

adjusting subsequent transmissions based at least in part on the received feedback.

21. The machine-readable medium of claim 20, the correspondence specifies for each transmission rank a number of layers associated with each codeword.

22. The machine-readable medium of claim 21, wherein at least one layer is associated with a codeword.

23. The machine-readable medium of claim 21, wherein at least two layers are associated with a codeword.

24. The machine-readable medium of claim 20, shuffling codeword blocks comprises symmetrically permuting codewords over all groupings such that each codeword transmits in part over all transmit antennas.

25. The machine-readable medium of claim 20, the condensed feedback metric comprises a base CQI reflecting a signal quality metric of a first decoded codeword and a differential CQI reflecting a signal quality gain obtained by cancelling interference of the first decoded codeword in decoding a second codeword.

26. The machine-readable medium of claim 25, adjusting subsequent transmissions comprises:

altering at least one of a data rate, code rate or modulation-scheme of a subsequent first codeword in response to the base CQI; and

altering at least one of a data rate, code rate or modulation scheme of additional subsequent codewords based upon a sum of the base CQI and a multiple of the differential CQI.

27. The machine-readable medium of claim 25, adjusting subsequent transmission comprises adjusting the at least one of a data rate, code rate or modulation scheme of subsequent first and additional codewords based upon the base CQI.

28. The machine-readable medium of claim 25, signal quality metric is one of a signal-to-noise ratio (SNR) or signal-to-interference-plus-noise ration (SINR).

29. The machine-readable medium of claim 20, grouping transmit antennas comprises identifying active antennas and disregarding inactive antennas.

30. The machine-readable medium of claim 29, wherein a size of an antenna group is determined from the correspondence between codewords and layers.

31. The machine-readable medium of claim 20, the transmit antennas include one or more physical or virtual antennas.

32. A method that generates reduced feedback in a wireless communication system, comprising:

unmixing permuted codeword blocks according to a permutation scheme employed during transmission;

regenerating interference created by a first codeword during transmission;

evaluating a channel quality indicator (CQI) related to the first codeword; and

evaluating a differential CQI related to quality increase resulting from cancelling the regenerated interference in decoding a second codeword.

33. The method of claim 32, further comprising receiving permuted codeword blocks through a plurality of receiver antennas.

34. The method of claim 32, the permuted codeword blocks are from at least two codewords.

35. The method of claim 32, further comprising decoding the unmixed codewords.

36. The method of claim 33, the CQI and the differential CQI based at least upon a SNR value or a SINR value.

37. In a wireless communication system, an apparatus comprising:

a processor configured to;

reconstruct at least two codewords received in a permuted form;

determine a base CQI reflecting the signal quality of a first codeword of the at least two codewords; and

calculate a delta CQI based upon the signal gain obtained in a second codeword.

38. A wireless communications apparatus that calculates reduced feedback by employing successive interference cancellations on permuted codewords, comprising:

means for receiving permuted codewords on a plurality of receiver antennas;

means for reconstructing codewords based upon the permuted codewords received;

means for regenerating interference created by a first codeword during transmission; and

means for cancelling the regenerated interference while decoding a second codeword.

39. The wireless communications apparatus of claim 38, further comprising:

means for determining a base CQI value indicating a signal quality of the first codeword; and

means for calculating a CQI boost reflecting an increase in signal quality in the second codeword resulting from cancelling the regenerated interference.

40. The wireless communications apparatus of claim 39, further comprising means for transmitting the base CQI and CQI boost on a reverse link channel.